Electric furnace for producing endothermic gas reactions.



R. PFAEHLER- & l. HECHENBLEIKNERQ ACE FOR PRODUCING ENDOTHERMIC GAS REACTIONS.

APPLICATION men'wmzs. 1m.

Patented Dec. 11, 1917.

R 3 SHEETS-SHEET'I.

ELECTRK) FURN R. PFAEHLER & I. HECHENBLEIKNER. ELECTRIC FURNACE FOR PRODUCING ENDOTHERMIC GAS REACTIONS. arrucmon HLED nusQzs. 191a.

$1,249,479, r I Patented Dec. 11,1917.

SSHEETS-SHEET 2 R. PFAEHLER 61 l HECHENBLEIKNER.

ELECTRIC FURNACE FOR PRODUCING ENDOTHERMIC GAS REACTIONS.

APPLICATION FILED 1116.26. ma.

1 3249, 179. Patented D60. 11, 1517.

3 SHEETS-SHEET 3- II II M? l/E/V mp5. P/CHA/Pp PrAE/a EA and UNITED STATES PATENT OFFICE.

RICHARD PFAEHLER, OF CIIARLOTTE, NORTH CAROLINA, ANIO I'NGENUIN HEGHEN- BLEIICNEB OF GREAT FALLS, SOUTH CAROLINA ASSIGNORS TO SOUTHERN ELEC- THO-CHEMICAL COMPANY, OF CHARLOTTE, NORTH CAROLINA, A CORPORATION OF NEW JERSEY.

ELEG'I'RIC FURNACE FOR PRODUCING ENDOTHERMIG GAS REACTIONS.

Specification of Letters Patent.

Patented Dec. 11, 1917.

Application filed August 26, 1913. Serial No; 786,767.

,5 Austria, respectively, residing at Charlotte,

1 in the county of Mecklenburg and State of North Carolina, and Great Falls, county of Chester, South, Carolina, respectively, have invented new and useful Improvements in Electric Furnaces for Producing Endothermic Gas Reactions, of which the following isa specification.

The present inventlon relates to an improved method of an electric furnace for, producing endothermic gas reactions in the production of nitrogen oxide from the air, and has for its objects to' greatly simplify .and improve methods and furnaces of'this type and render the same more certain, re

liable and efiicient in operation.

In the processfor producing endothermic gas reactions, as for instance the formation of nitrogen oxids from the air by means of the electric arc, the amount of formed nitric oxide increases with the rise of temperature.

These reactions belong, however, to the class of reversible reactions. Unless the highly heated. gases are rapidly cooled down,

80 a decomposition or dissociationof the formed nitric oxid gases takes place. I

In the methods thus far in use, it is sought to veifect the cooling or chilling by mixing the hot reaction gases with the-cold part of 85 the air first introduced or With separately introduced cold air, or by sub ect1ng the. hot reaction gases to cooled metal surfaces or rotating metal disks.

The various types of apparatus devised to attain this ObJBCt are, however, not very efficient. and are more or less the cause of serious troubles in connection with the operation of the electric furnace. 4 I

In the furnace herem described and wh1ch 4-5 forms the subjectmatter of the presentinventi'on, newlrnethods and means are. em-

ployed to cool down the hot gases so rapidly that the formed nitric oxid has practically no time to undergo decomposition and in addition the length of the electric arc is materially increased.

- Referring to Letters Patent No. 887 ,220, dated lllay 12, 1908, and N 0. 1,029,886, dated J unc 18, 1912, relating to a pair of auxiliary electrodes that are electrically connected to a pan of diverging electrodes for starting the electric arc, the tips of the auxiliary elec trodes or commonly called kin are cooled by the current of through the space between the trodes.

It has been founclthat this current of air,

must be forced through the above mentionct space under a comparatively high pressure so as to prevent the kindling blades from being too quickly burned up. In the methods now in use, all the air *to be treated in the electric arc, is blown into the reaction chamber through one nozzle. This arrangement consequently requires a considerable amount of auxiliary power for driving the :blower furnishing this air current of high pressure.

One object of the present invention is to reduce the power needed for driving the auxiliary' machinery by introducing the strong air current which is especially re quired for the cooling of the tips of the kindling blades, through a separate nozzle. 7 Referring to. Letters Patent'No. 1,029,885, dated June 18, 1912, describin -a water cooled electrode constructed of t ree parts, experience has-shown that the upperpart is the cause of frequent electric short c rcuits and that it is rather diflicult to satisfactorily insulate rtliis upper part from the furnace walls so as to revent burning out. of

the insulation and jacent pants Another object of the invention is to prevent these troubles by cntirely' oniitting this upper part of the electmde 'an' improved" constructionproviding' ing drawing forming part of this specification, wherein- Figure 1 is a top plan view of the furnace, including the gas cooler and auxiliary machinery.

Fig. 2 is a. vertical section along the line A-BC-D, Fig. 1.

Fig. 3 is another vertical section along the line E-F, Fig. 2.

Fig. 4 is a front elevation of the electrode stand.

Fig. 5 is a vertical section on an enlarged scale, through the lower portion of the furnace chamber, one of the electrodes being shown in elevation.

Figs. 6, 7, and 8 are cross-sections through the electrode and electrode tubes, respectively, and

Fig. 9 is a top plan view of the low pressure air nozzle.

These last named three sections and one view are drawn at a still more enlarged scale.

Like letters of reference denote corresponding parts in all the views and sections, respectively.

As shown in the drawings, the furnace chamber consists of an iron casing 1, which is built up on the base plate 2. The base plate 2 rests on the beams 3 and 4, which are 'supported by the brackets 5, 6, 7 and 8.'

These four brackets are securely fastened to the four vertical columns 9, 10, 11 and 12.

The casing 1 is lined with firebrick or some suitable refractory material 13, two opposite Walls of which are inclined or flare outwardly and upwardly from the base as more clearly shown in Fig. 2.

The extension of the casing 1 consists of the reducer 14 slightly contracted at its uper end, and of the flue 15, which is connected with the gas cooler 16. The reducer l4 and the flue 15 are also lined with refractory material 17 which forms an extension of the line 13, the parts 1 and 14, with their linings 13, and 17' forming a furnace chamber of novel construction.

The horn shaped stationary electrodes which are also of novel shape and construction, are shown in detail in Figs. 5 to 8, in-

elusive. In Fig. 5 one electrode is shown in section an'dthe other electrode in elevation.

Both electrodes are duplicates and similar parts are marked by the same numeral.

The electrode proper consists of the main part 18 and the lower part 19, both of which parts are made of cast iron. The lower part. 19 is provided with a pipe tap'suitable for the insertion of the tube 20. The tube 21 of smaller diameter is located inside of the tube 20. The annular space between the tubes 20 and 21 is divided in two spaces 23 and 29 by the partitions 22 and 23, which extend throughout the entire length of the tube 20. Both ends of the tube 20 are closed by the rings 24 and 25. Near the end of tube 20 outside of the furnace chamber, the pipe-nozzles 26 and 27 are welded on the tube 20. The nozzle 26 Fig. 8, connects with the space 28 and the nozzle 27 with the space 29.

The nozzle 26 is suitably connected with some cooling water supply. This water passes then through the space 28 and flows through the opening 30in the tube 20 into the corresponding canal 31 provided in the lower part 19. The main part 18 is clamped to the lower part 19 by the bolts 3-1 and the canal 32 is an extension of canal 31. The water thus fiows through the canal 32 in the part 18, of the electrode and returns through the canal 33.

Another canal opposite and similar to canal 31 formed in the lower part-19 of the electrode, conveys the water through an opening opposite the opening 30 into the space 29 andthe water then finally discharges through the nozzle 27.

The adjustable auxiliary electrodes or kindling blades 35 are located inside of the tube 21 and pass-through a slot formed in the lower part 19 between the two canals 31. The outer end of the kindling blade 35 is attached to the rack.36 with which a pinion 36, engages, by means of whichthe electrodes may be adjusted toward and from each other.

Referring again to the main part 18, it will be noticed in Figs. 5 and 7 that the portion or wall of the electrode that is exposed ,to the action of the flame is of increased thickness and the life of the elec trode is thereby lengthened, that is to say, the electrodes do not burn out so quickly.

The electrode tubes 20 are insulated from the metal doors 37 by the insulating bushing 78 as more clearly shown in Figs.

2 and 5.

Experience has shown'that the" shape of the reaction chamber should conform tothe shape of the electrodes so as to prevent eddies and other air disturbances, which tend to deflect the are, and cause short circuits. The reaction chamber 38 is built upon these principles. The opening left for the insertion of the electrode will be closed by the door brick 39, which is securely fastened to the iron door 40. In order to be able to quickly replace and remove this door-brick 39, the trolley carriage 42 traveling along the runway 43 is employed. At the upper end, the iron door 40 is provided with two projections, in which the holes 44 and 45 are drilled, and at the lower end with a third projection 46.

The trolley carriage 42 is provided with the angle levers 47 and 48. By bringing the carriage 42 toward the iron door 40, the holes 49 and 50 drilled in the levers 47 and 48 will come opposite the holes 44 and 45 and a suitable pin will be placed through all of these holes, thus connecting the door 40 to which the firebrick 39 is attached, with the trolley carriage 42.

When the furnace is in operation the iron door 40 is suitably bolted or clamped to the iron casing 1.

With the trolley carriage 42 connected to 'the door 40 by the above described method,

the attachments on the door 40 can be romoved and due to its own weight the door 40 with its projection 46 will rest against the stop 51 provided at the bottom of the carriage 42.

For the purpose of making small adjust ments the trolley carriage 42 is provided with the turnbuckle arrangement 52.

The placing or removing of the elect-rode is done by using the electrode carriage 53 as more clearly shown in Fig. 2. The elec' trode stand 54 is provided with three projections similar to those used on the iron door 40. The removed electrode attached to the electrode carriage 53 is shown in dotted lines 38 through the pipeline 56 and nozzle 57 respectively, as more clearly shown in Figs. 3 and 5.

The low pressure air is furnished by the blower 58, Figs. 2, 3, and 5. This air is then passed through the pipe line 59 and dis charged through the nozzle 60 into the space.

between the main electrodes. As will be seen pipe line 63 is tapped by the pipe-line 64,

which is connected to the exhauster 65. The outlet of the fan 65 is connected with the pipe line 66, which branches olf to the conduits 67 and 68 attached to the base plate 2. The extension of these conduits 67 and (38 through the base plate and through the furnace lining 17 is formed by the dimts 65) and 70, traversing the lower portion of the furnace chamber as more clearly seen in Fig. 3.

These ducts 69-.and 70 connect with the reaction chamber 38' through the elongated slots 71 and 72, which extend over the entire distance between the electrode parts 18 just: above the zone of maximum heating of the electric arc.

The low pressure air pipeline 59 connected with the conduits 7 and 68 by the branches 73 and 74. The gates or valves 75 and 76 are built in the branch pipes 73 and 74 and as shown in Fig, 3, both are closed but may be adjusted to regulate the volume of air introduced into the furnace chamber.

Now, part of the gases leaving the gas cooler 16 through the pipe line 63 are drawn off by the exhauster 65 throu h the pipe line 64. The valve 77 placed in t e pipe line 64' may be used for regulatingthe volume of gases to be returned.

By the action of the fan 65 the return gases are then forced through thepipe line 66, through the conduits 67 and 68 and through the ducts 69 and 70 and finall blown into the reaction chamber 38 thrt'iug the slots 71 and 72 just above the zone of maximum heating of the electric garc.

The result of .this arrangement is that the comparatively cold return gases suddenly cool-oft the hi ghly heated reaction gases to a temperature which is below the critical'tenr perature, so that a decomposition of the nitric oxid gases formed in the electric arc is reduced to a minimum.

On the other hand, the gases returned into the chamber 38 through the slots 71 and 72, practically contain the same percentage of nitric oxidgases, by volume, as the gases treated in the electric arc, and the treated gases will not, therefore, be diluted by this method.

If, for some other reason, it is desired to mix the return gases with a. part of the low pressure air or gas mixture passing through the pipe line 59, the gates'or valves 7 5 and 7 6 may besuitably opened.

The return gas supply through the pipe line (14 may be also entirely cut off by closing the valve 77.

As illustrated, especially in Fig. 3, the direction of the cool gases or gas mixtures forced through the slots 7]. and 72 into the reaction chamber 38, is such as to produce the effects of an injector. The length of the electric are formed between the electrode pair 18, will by this arrangement be considerably increased, thus im n'oving the electrical conditionsof the furnace.

Vhat we claim is:

1. An electric furnace of the character described having a reaction chamber, opposite walls of which diverge from the base of the furnace upwardly, each of said diverging Walls having an opening thercthrough and a movable closure therefor, and a pair of op posed electrodes arranged in said chan'iber, one opposite each closure, and each cle trode having a diverging part conforming substantially to the contour ofa diverging wall, of the chamber of the furnace and adapted to be witlnlran'n therefrom through the opening in its diverging wall.

2. An electric furnace of the character described having a reaction chamber, apair of oppositely disposed hollow electrodes arranged within said chamber, each electrode havinga divergin part terminating wholly within the chamber, and a return passage in said part, and means for circulating ,a cooling medium through the return passage in the diverging part of said electrodes.

3. In an electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arranged within said chamber, a pair of kindling-blades associated with said electrodes, and separate nozzles for delivering air into the furnace chamber, one of said nozzlesbeing arranged to deliver a current of cooling air against the said kindling-blades.

4:. In an electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arranged within said chamber, a pair of kindling blades associated with said electrodes, separate nozzles for delivering air into the furnace chamher, one of said nozzles being arranged to deliver a current of high pressure air against the said kindling blades for cooling the latter.

5. In an electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arranged within said chamber, a pair of-kindling blades associated with said electrodes, separate nozzles for delivering air into the furnace chamber, one of said nozzles. being arranged to deliver a current of high pressure air against the said kindling blades for cooling the latter, and separate sources of supply for the said nozzles.

6. In an electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arranged within said chamber, each electrode having a portion extending through and insulated from the furnace all, a nozzle for delivering air into the furnace chamber, and means for directing a current of cooling air against the insulated portion of each electrode.

7. In an electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arranged within said chamber, each electrode having a portion extending through and insulated from the furnace wall, a nozzle for delivering air into the furnace chamber, and means forming a part of said nozzle. for directing a current of cooling air against the insulated portion of each electrode.

8. In an electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arranged within said chamber, each electrode having a portion tending through and insulated from the fur-- nace wall, a nozzle for delivering air into the furnace chamber, and separate laterally directed outlet ports associated with said nozzle for delivering a current of cooling air against the insulated portion of each electrode.

9. In an electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arranged within said chamber, doors in the opposite walls of the chamber through which said electrodes may be inserted and removed, a door-supporting carriage movable toward and from each of the said doors, and means for detachably connecting each door to its associated carriage. v I 1 10. In an electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arran ed within said chamber, doors in the opposlte walls of the chamber through which said electrodes may be inserted and removed, a door-supporting carriage movable toward and from each of the said doors, a trolley for each carriage, and means for detachably connecting each door to its associated carriage.

11. In an electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arranged within said forwithdrawmg and replacing the same.

12. An electric furnace of the character described havin a reaction chamber, and a pair of 0p ose electrodes arranged within said cham er, each electrode having a diverging member terminating wholly within the chamber and each electrode member rovided with a return passage through w ich.

a cooling medium may be circulated. a

13. An electric furnace of the character described having a reaction chamber, a pair of opposed electrodes arranged therein, each electrodecomprising a base member 19 and a diverging member 18, removably attached to the said base member and terminating v Oeplee of thin patent may be obtained for live cents each, by amen; the

Washington, D. 0;

Wholl; within the said chamber, and means 15 for circulating a cooling medium through the two members of each electrode. In testimony whereof we have hereunto set our hands in presence of subscribing wit nesses.

' RICHARD PFLEHLER.

' IN GENUIN HEGHENBLEIKNERF Witnesses for Pfaehler:

J. GRANVILLE Mums,

V E. H. BICKERTON.

Witnesses for Hechenbleikner:

E. A. WOHLFORD,

D. C. CARMICHAELQ Gommlllioner o1 intents, 

